Present day portable generators typically make use of a starter motor and a fixed lead acid battery to start an internal combustion (IC) engine that drives an alternator, thereby producing an electrical power output. The starter motor and fixed battery add size, bulk and weight to the portable generator. As can be appreciated, since the generator is intended to be transportable, keeping the generator as light and as small as possible is highly desirable.
In the latest portable generator technology, the alternator is replaced with a smaller and lighter permanent magnet generator (PMG) and an electronic power converter. In normal operation, the IC engine directly drives the PMG which then produces electrical power. This variable frequency (engine speed dependent), variable voltage power is then converted electronically to a constant voltage, constant frequency output, for example a 120 VAC, 60 Hz output. Typically, a PMG includes a single set of windings that are used to produce the electrical power output of the portable generator.